Which of the following is the best definition of a cone?

A cone is a two-dimensional figure with circles on both ends.

A cone is three-dimensional figure. It has parallel sides, and the ends are either circles or ovals.

A cone is a three-dimensional figure with a flat base and four sides that connect at a point.

A cone is a three-dimensional figure. It has a circular base on one side, and it tapers to a point on the other side.